Compact PNP BJT-Based Temperature Sensor and Sub-1-V Bandgap Reference for SoC Applications in 4-nm FinFET

This article presents a dual-function circuit of a temperature sensor and a sub-1-V bandgap reference (BGR) implemented in the 4-nm FinFET CMOS process. The design, based on subthreshold MOS transistors and parasitic PNP bipolar junction transistor (BJT) devices, offers distinct advantages over existing PNP BJT-based sensors and sub-1-V BGRs. As a temperature sensor, it achieves the fastest conversion time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7~{\mu }$ </tex-math></inline-formula> s, while consuming a power of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$68.5~{\mu }$ </tex-math></inline-formula> W, which results in the lowest energy consumption rate of 0.5 nJ per conversion. In addition, the sensor demonstrates a resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.46~{^{\circ }}$ </tex-math></inline-formula>C and a resolution figure-of-merit (FOM) of 0.106 nJ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> K2. It also functions as a low-cost, high-accuracy BGR capable of sub-1-V operation, producing a stable output of 450 mV within a compact 0.0061 mm2 footprint, and featuring an accuracy of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm 1.1\% (\pm 3\sigma)$ </tex-math></inline-formula> along with an average temperature coefficient (TC) of 33 ppm/°C. Moreover, by supporting both BGR and sensing modes, the design significantly reduces costs by incorporating dual functionalities within a single architecture.